I run the ADC200/12 on a Win95 system and have no dc-respons on my measurments The unit seems to be ac-coupled.
Tried the latest version Release 5.12.7-32bit with an ADC200 Driver V4.02 and ADC 200-20 V5 with the same problem.
I have also tried the same with a ADC212 unit with better luck, i.e. it works on dc signals.
Is the problem in the program or in the ADC-unit??